1. Field of the Invention
The present invention relates to an ammonia GAX (General Absorber Heat Exchanger) absorption cycle.
2. Discussion of Related Art
FIG. 1 is a schematic of a conventional ammonia GAX absorption heating and cooling cycle.
Referring to FIG. 1, the GAX heating and cooling Cycle comprises a generator 10 for heating an NH.sub.3 -water strong solution to a boiling point to generate ammonia vapor, a rectifier 14 for condensing and rectifying steam contained in an ammonia vapor produced by the generator 10, a condenser 30 for condensing a coolant vapor generated from the rectifier 4 into a liquid coolant, an evaporator 40 for producing cool water by actually vaporizing a coolant, an absorber 20 for absorbing the coolant vapor generated from the evaporator 10, an expansion valve 60 for dropping the pressure of the generator 10 and condenser 30 which are high pressure units, a distributer 24 for uniformly dispersing a weak solution introduced into the absorber 20 through the expansion valve 60, a solution cooling absorber 50 provided in the absorber 20 to make heat exchange between the strong solution transferred from the absorber 20 into the generator 10 and the weak solution produced by the generator 10, an analyzer 13 for allowing the strong solution to flow into the generator 10 via the solution cooling absorber 50 so as to make heat exchange with the coolant vapor produced by the generator 10, a water cooling absorber 21 for permitting the cooling water into the absorber 20 to make heat exchange with the coolant vapor introduced from the evaporator 40 into the absorber 20, a solution pump 70 for jetting the solution out of the low pressure unit, absorber 20 to the high-pressure unit, generator 10, heat-exchangers 12 and 23,a circulation pump 90, a coolant heat-exchanger 50, a weak solution coil 11, and a burner 80.
A typical ammonia GAX absorption cycle basically comprises four constituent units, the generator 10, condenser 30, evaporator 40 and absorber 20.
As shown in FIG. 1, the burner 80 heats a working solution, which is the strong solution produced in the generator 10, to produce a coolant vapor and a weak solution. The coolant vapor moving upward enters the rectifier 14 to make a heat-exchange with cooling water, which is used to eliminate a condensing heat in the condenser 30, whereby a vaporized steam and the coolant vapor are condensed and rectified into a concentrated coolant vapor in the rectifier 14.
The weak solution produced by the generator 10 has a specific gravity larger than that of the strong solution and flows down to the bottom of the generator 10. The weak solution flows in the weak solution coil 11 by means of the pressure difference between a high-pressure unit, i.e., generator 10 and a low-pressure unit, i.e., the absorber 20, being expanded at the expansion valve 60 and flowing into the absorber 20.
The distributer 24 provided at the top of the absorber 20 allows the weak solution to pass into the absorber uniformly.
The concentrated coolant vapor rectified in the rectifier 14 enters the condenser 30 to make heat exchange with cooling water. A liquid coolant generated as such passes through the expansion valve 60 to the evaporizer 40 heated, where heat exchange occurs between the liquid coolant and the cooling water to generate the coolant vapor again.
The coolant vapor vaporized in the evaporizer 40 flows into the coolant heat exchanger 50 to undergo heat exchange with the liquid coolant condensed in the condenser 30. The liquid coolant is cooled nearly to a vaporization temperature in the evaporizer 40, but coolant vapor is heated up to a saturation temperature of the absorber 20, thereby accelerating the absorption and efficiently vaporizing a small amount of the coolant which is not completely vaporized in the evaporizer 40.
The coolant vapor vaporized in the evaporizer 40 undergoes heat exchange in the coolant heat exchanger 50 and flows into the absorber 20. It is then absorbed by the weak solution produced in the generator 10, so that the weak solution is converted into a strong solution as thick as the original strong solution in the generator 10.
The removal of heat is required to accelerate the absorption of the coolant vapor into the strong solution. To eliminate the heat, the coolant vapor from the evaporizer 40 is absorbed by the solution flowing downward in a solution cooling absorber 22, and the heat of absorption generated as such is exchanged in the water cooling absorber 21. The pumping of the solution pump 70 generates the strong solution in the absorber 20 and the strong solution enters the generator 10. Flowing in the solution cooling absorber 22 provided within the absorber 20, the strong solution undergoes heat exchange with the water cooling absorber 21. Thus, the weak solution in the absorber 20 bore efficiently absorbs the coolant vapor flowing upward the water cooling absorber 21 to generate the strong solution in the absorber 20.
Through the pumping of the solution pump 70, the strong solution generated in the absorber 20 flows through the solution cooling absorber 22, and enters the analyzer 13 formed in the absorber 20 to have heat exchange with the coolant vapor produced in the generator 10.
To remove heat, the cooling water is heated in the water cooling absorber 21, but cooled again with a fan.
During the cooling, an indoor air is supplied with cooling water cooled in the evaporizer 40. The cooling water cools the condenser 30 and the absorber 20 and the cooling water heated thereby is exhausted to outdoor air so as to be cooled again.
Unlikely, during the heating the hot water passing through the condenser 30 and the absorber 20 is transferred to the indoor air. The outdoor air is supplied with the cooling water passing through the evaporizer 40.
The working fluid in the heat exchanger 23 formed in the top of the absorber 20 is produced in the generator 10 and gets heated during the heat exchange with the heated weak solution in the absorber 20. The working fluid is circulated by the circulation pump 90, and enters the heat exchanger 12 formed in the generator 10 to undergo heat exchange with the strong solution flowing from the solution cooling absorber 22 of the absorber 20 to the analyzer 13 of the generator 10. The strong solution is thus heated.
To transfer heat from the absorber 20 to the generator 10, the conventional ammonia GAX absorption cycle is required to use a separate heat transfer fluid instead of the working fluid and additionally a separate heat transfer circuit to carry the fluid. The heat transfer circuit must be a closed circuit comprising an expansion chamber (not shown) to absorb the thermal expansion and contraction according to the temperature of the heat transfer fluid. A circulation pump 90 is required to give a compulsory circulation of the heat transfer fluid. This cycle is to transfer only the line heat of the absorber 20 to the generator 10.
As described above, the conventional GAX cycle is very expensive to operate because it has to be provided with a separate heat transfer circuit, heat transfer fluid, expansion tank, circulation pump and the like. Furthermore, it uses only the line heat, but cannot expect a considerable improvement in the coefficient of performance against the cost.